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Microscopic High-Speed Liquid-Metal Jets in Vacuum
KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
KTH, School of Engineering Sciences (SCI), Physics. KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.ORCID iD: 0000-0003-2723-6622
2005 (English)In: Experiments in Fluids, ISSN 0723-4864, E-ISSN 1432-1114, Vol. 39, 799-804 p.Article in journal (Refereed) Published
Abstract [en]

We describe a novel electron-impact x-ray source based on a high-speed liquid-metal-jet anode. Thermal power load calculations indicate that this new anode concept potentially could increase the achievable brightness in compact electron-impact x-ray sources by more than a factor 100 compared to current state-of-the-art rotating-anode or microfocus sources. A first, successful, low-power proof-of-principle experiment is described and the feasibility of scaling to high-brightness and high-power operation is discussed. Some possible applications that would benefit from such an increase in brightness are also briefly

Place, publisher, year, edition, pages
2005. Vol. 39, 799-804 p.
Keyword [en]
brightness, X-ray source, electron-impact, liquid-metal jet
National Category
Physical Sciences
Identifiers
URN: urn:nbn:se:kth:diva-5836DOI: 10.1007/s00348-005-0013-9ISI: 000233239900002Scopus ID: 2-s2.0-27744509715OAI: oai:DiVA.org:kth-5836DiVA: diva2:10348
Note
QC 20100915Available from: 2006-05-30 Created: 2006-05-30 Last updated: 2017-12-14Bibliographically approved
In thesis
1. A Compact High-Brightness Liquid-Metal-Jet X-Ray Source
Open this publication in new window or tab >>A Compact High-Brightness Liquid-Metal-Jet X-Ray Source
2006 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis describes the development and characterization of a compact high-brightness liquid-metal-jet anode x-ray source. Initial calculations show that a source based on this concept could potentially lead to a >100-fold increase of the brightness compared to current state-of-the-art rotating-anode x-ray sources. This improvement is due to an increased thermal load capacity of the anode.

A low-power proof-of-principle source has been built, and experiments show that the liquid-metal-jet anode can be operated at more than an order of magnitude higher power densities than modern solid-metal anodes. This brightness enhancement has been utilized to acquire in-line phase-contrast images of weakly absorbing objects with substantially shorter exposure times than previously reported. To be able to target different application areas different liquid-jet-anode materials have been tested. The Sn-jet anode could potentially be used in mammography examinations, whereas the Ga-jet could be utilized for, e.g., protein-structure determination with x-ray diffraction.

Scaling to higher power and brightness levels is discussed and seems conceivable. A potential obstacle for further development of this source concept, the generation of a microscopic high-speed liquid-metal jet in vacuum, is investigated and is proven to be feasible. Dynamic-similarity experiments using water jets to simulate 30-μm, ~500-m/s tin and gallium jets show good coherence and directional stability of the jet. Other potential difficulties in the further source development, such as excessive debris emission and instabilities of the x-ray emission spot, are also investigated in some detail.

Place, publisher, year, edition, pages
Stockholm: KTH, 2006. xii, 61 p.
Series
Trita-FYS, ISSN 0280-316X ; 2006:36
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-4005 (URN)91-7178-371-7 (ISBN)
Public defence
2006-06-09, Sal D3, Lindstedtsvägen 5, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
QC 20100915Available from: 2006-05-30 Created: 2006-05-30 Last updated: 2010-09-15Bibliographically approved
2. Liquid-Jet-Target Microfocus X-Ray Sources: Electron Guns, Optics and Phase-Contrast Imaging
Open this publication in new window or tab >>Liquid-Jet-Target Microfocus X-Ray Sources: Electron Guns, Optics and Phase-Contrast Imaging
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This Thesis describes the development of an electron-impact microfocus x-ray source and its application for phase-contrast imaging. The source is based on a novel, liquid-jet target concept. Stable and continuous operation can be achieved at substantially higher electron-beam power densities than conventional solid target based systems. The maximum x-ray brightness can potentially be increased by a factor of 10-1000, which would provide significantly improved performance in applications such as imaging. In order to reach the high x-ray brightness, comparable performance from the electron gun is needed. A LaB6-cathode-based electron gun is analyzed in terms of achievable e-beam brightness and beam quality and is found capable to deliver power densities in the 10-100 MW/mm2 range using optimized electro-optics. A proof-of-principle microfocus source has been developed. Experiments show that the liquid-metal-jet target can be operated at more than an order of magnitude higher e-beam power densities than modern solid-metal targets. This brightness enhancement has been utilized to acquire in-line phase-contrast images of weakly absorbing objects. The source potentially enables the application of high-resolution phase-contrast x-ray imaging with short exposure times in clinics and laboratories.

Different liquid-jet-target materials have been tested. The Sn-jet (Ka=25.3 keV) could be suitable for mammography, whereas the Ga-jet ((Ka=9.2 keV) may be utilized for x-ray diffraction studies. In addition, a non-metallic methanol jet has been the demonstrated in stable x-ray operation. All materials and compounds found in liquid form can, thus, potentially be used for electron-impact liquid-jet-target x-ray generation.

Scaling to higher e-beam power density and x-ray brightness levels is discussed and is determined to be feasible. Potential difficulties, such as debris emission and instabilities of the x-ray emission spot, are investigated in some detail. Larger and/or faster jets could overcome the present limitations because of their inherently higher heat load capacities. Dynamic-similarity experiments show that liquid jets can in principle be operated in a stable manner at much higher speeds than previously shown.

Place, publisher, year, edition, pages
Stockholm: KTH, 2008. x, 91 p.
Series
Trita-FYS, ISSN 0280-316X ; 2008:12
Keyword
electron-impact, x-ray, brightness, liquid-jet-target, phase-contrast imaging
National Category
Other Engineering and Technologies
Identifiers
urn:nbn:se:kth:diva-4802 (URN)978-91-7415-004-9 (ISBN)
Public defence
2008-06-13, FR4, Albanova, Roslagstullsbacken 21, Stockholm, 14:00 (English)
Opponent
Supervisors
Note
QC 20100915Available from: 2008-06-04 Created: 2008-06-04 Last updated: 2010-09-15Bibliographically approved

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Hertz, Hans M.

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